The present invention relates to seal members and especially to cup seals and packings used in hydraulic and pneumatic application to seal between relatively movable members.
Cup-type seals and packings have been in existence for many years and are commonly used to seal in cylinders or working barrels, the cup seals being carried by the moving element such as a pump rod or the like. For example, such seals are employed extensively in downhole pumps to seal between the pump rod and the barrel of the pump. In such conventional cup seals, the sealing portion in contact with the cylinder wall of the cup seal is generally on the OD of the seal. There are, however, other applications utilizing modified cup seals and packings wherein sealing occurs on an ID surface of the seal such as, for example, where the sealing surface formed by the lip of the cup seal contacts a moving rods, shaft, etc. in sealing engagement.
Generally speaking, in a typical sealing arrangement, a plurality of cup seals are assembled between metal spacers in a stacked array. To effect proper sealing, the stacked array is mechanically compressed along its axial dimension. In the case of a stacked array using a cup seal with an OD sealing lip, the cup seal has a radially inwardly extending clamping flange forming part of the "heel portion" of the seal. The axial compression of the stacked array occurs by mechanical compression applied to the axially facing surfaces of the radially inward flange. This compressive force coupled with the fluid pressure tends to distort the cup seal in a radially outer direction in the area adjacent the heel portion. Excessive forces can result in a high friction or high wear area which can result in premature cup failure. To overcome this problem, cup seals have been made of various materials designed to resist excessive distortion and premature wearing. Thus, cup seals have been constructed of all cotton fabric, cotton fabric and nylon combination, all with suitable elastomeric binders, as well as from nylon, leather, etc. These approaches have not proven altogether satisfactory in solving the problem described above in connection with excessive wear spots.
It is known to provide various types of seals and packings of dual material construction. British Pat. No. 2,022,770 discloses a pig cup for pipeline pigs, the pig cup having a skirt portion which is made of a relatively soft elastomer and which is arranged to sealingly engage a pipe wall in use, the skirt portion being carried by a body portion which is made of a relatively hard elastomer.
U.S. Pat. No. 4,066,269 to Linne discloses a dual material seal member having a support section formed of a high modulus material and a sealing section formed of an elastomeric material, the two materials being bonded directly together without the use of an adhesive therebetween.